Seminar on Saving Hemlock Trees with Biocontrols for Hemlock Woolly Adelgids
The Hemlock Woolly Adelgid is a significant threat to our local hemlock trees, which are foundational species in our forests. Hemlocks provide essential food and protection for wildlife in winter, when they are actively growing. They offer shade to cool streams and ponds in summer. Unfortunately, the Hemlock Wooly Adelgid, introduced to the East Coast in 1951, is threatening our Hemlock woods due to warmer winter temperatures. In the past, our 20-below artic vortices would kill off the Adelgids, but winters have warmed up faster than summers and Adelgids are now causing widespread hemlock decline. Entire ecosystems are threatened by the destruction of the Hemlock woods that support over 120 species of animals and birds. These two trees on the side of Lake Skatutakee in Harrisville, NH are a harbinger of what future forests might look like without Hemlock trees.
Dr. McDonald has been at the forefront of research and relocation programs for HWA predators from the Pacific Northwest. He and his associations have been releasing Laricobious Nigrinus beetles in North Carolina Hemlock forests for over 20 years. Laricobious beetles feed exclusively on adelgids and have been instrumental in controlling HWA populations in several states. Dr. McDonald will discuss successful biocontrol efforts in North Carolina and other states and the potential for similar success in New Hampshire.
The Harrisville Conservation Commission is working with Dr. McDonald to import Laricobious Nigrinus from North Carolina for release at a dozen Hemlock woods locations across Harrisville. The goal is to establish breeding populations of beetles that can restore balance by suppressing Hemlock Wooly Adelgids.
Unlike most predator beetles of HWA, Lari is a winter feeder. This tiny (2-3mm) beetle has adapted to NC and both the adult and the larvae feed on HWA from October to May. The adults can eat 6 or more adelgids per day before laying 200-400 eggs singly in HWA egg sacs. Each larva can consume 200-250 HWA eggs or crawlers before they pupate in June. After release they are expected to spread to surrounding woods at a rate of 1 to 2 miles per year.
NH Forest Health Specialist Ryan Crandall of the NH Division of Forests and Lands has approved Harrisville’s release program under New Hampshire’s federal USDA license to release Laricobious in-state. This seminar marks the beginning of a major project by the Harrisville Conservation Commission to protect our hemlock trees.
Dr. McDonald and the Harrisville Con Com are working together to identify ideal beetle release locations and facilitate the transfer of beetles to Harrisville in early November through December. To learn how this release effort will proceed, visit Beetles Save Needles.